php生成缩略图类,支持自定义高和宽,还支持按高和宽截图,实例代码如下:

1. <?php   
2. class resizeimage   
3. {   
4.     //图片类型   
5.     var $type;   
6.     //实际宽度   
7.     var $width;   
8.     //实际高度   
9.     var $height;   
10.     //改变后的宽度   
11.     var $resize_width;   
12.     //改变后的高度   
13.     var $resize_height;   
14.     //是否裁图   
15.     var $cut;   
16.     //源图象   
17.     var $srcimg;   
18.     //目标图象地址   
19.     var $dstimg;   
20.     //临时创建的图象   
21.     var $im;   
22.     function resizeimage($img, $wid, $hei,$c,$dstpath)   
23.     {  //开源代码phpfensi.com 
24.         $this->srcimg = $img;   
25.         $this->resize_width = $wid;   
26.         $this->resize_height = $hei;   
27.         $this->cut = $c;   
28.         //图片的类型  
29.  
30. $this->type = strtolower(substr(strrchr($this->srcimg,"."),1));   
31.         //初始化图象   
32.         $this->initi_img();   
33.         //目标图象地址   
34.         $this -> dst_img($dstpath);   
35.         //--   
36.         $this->width = imagesx($this->im);   
37.         $this->height = imagesy($this->im);   
38.         //生成图象   
39.         $this->newimg();   
40.         ImageDestroy ($this->im);   
41.     }   
42.     function newimg()   
43.     {   
44.         //改变后的图象的比例   
45.         $resize_ratio = ($this->resize_width)/($this->resize_height);   
46.         //实际图象的比例   
47.         $ratio = ($this->width)/($this->height);   
48.         if(($this->cut)=="1")   
49.         //裁图   
50.         {   
51.             if($ratio>=$resize_ratio)   
52.             //高度优先   
53.             {   
54.                 $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);   
55.                 imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this->resize_height, (($this->height)*$resize_ratio), $this->height);   
56.                 ImageJpeg ($newimg,$this->dstimg);   
57.             }   
58.             if($ratio<$resize_ratio)   
59.             //宽度优先   
60.             {   
61.                 $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);   
62.                 imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width)/$resize_ratio));   
63.                 ImageJpeg ($newimg,$this->dstimg);   
64.             }   
65.         }   
66.         else  
67.         //不裁图   
68.         {   
69.             if($ratio>=$resize_ratio)   
70.             {   
71.                 $newimg = imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio);   
72.                 imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width)/$ratio, $this->width, $this->height);   
73.                 ImageJpeg ($newimg,$this->dstimg);   
74.             }   
75.             if($ratio<$resize_ratio)   
76.             {   
77.                 $newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height);   
78.                 imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height)*$ratio, $this->resize_height, $this->width, $this->height);   
79.                 ImageJpeg ($newimg,$this->dstimg);   
80.             }   
81.         }   
82.     }   
83.     //初始化图象   
84.     function initi_img()   
85.     {   
86.         if($this->type=="jpg")   
87.         {   
88.             $this->im = imagecreatefromjpeg($this->srcimg);   
89.         }   
90.         if($this->type=="gif")   
91.         {   
92.             $this->im = imagecreatefromgif($this->srcimg);   
93.         }   
94.         if($this->type=="png")   
95.         {   
96.             $this->im = imagecreatefrompng($this->srcimg);   
97.         }   
98.     }   
99.     //图象目标地址   
100.     function dst_img($dstpath)   
101.     {   
102.         $full_length  = strlen($this->srcimg);   
103.         $type_length  = strlen($this->type);   
104.         $name_length  = $full_length-$type_length;  
105.  
106.         $name         = substr($this->srcimg,0,$name_length-1);   
107.         $this->dstimg = $dstpath;  
108.  
109. //echo $this->dstimg;   
110.     }   
111. }  
112.  
113. $resizeimage = new resizeimage("11.jpg", "200", "150", "1","17.jpg");  
114.  

原文链接：http://www.phpfensi.com/php/20140819/4428.html